Stomach cancer, or gastric cancer, develops in the lining of the stomach. The stomach is a sac-like organ that holds food for digestion and is located in the upper abdomen, between the esophagus and the small intestine. Gastric cancer is more common among older adults, with approximately two-thirds of gastric cancer patients in the United States being older than age 65.
Stomach cancer is uncommon in the United States and Europe, but is more prevalent in Asia and South America. There are a number of different types of gastric cancer. Most gastric cancers are adenocarcinomas, or cancer that arises in glandular tissue, or the cells lining the mucosa (innermost layer of the stomach). Other less common types are soft tissue sarcomas (leiomyosarcoma), lymphomas, gastrointestinal stromal tumors (GIST lesions), and carcinoid tumors.
Signs and symptoms of stomach cancer may include:
- Abdominal pain
- Anemia (iron-deficiency, related to cancer bleeding)
- Feeling bloated after eating
- Feeling full after eating little
- Stomach pain
- Weight loss (non-intentional)
Factors that increase the risk of stomach cancer include:
- A diet high in salty, cured, smoked, preserved, or pickled foods
- A diet low in fruits and vegetables
- Family history of stomach cancer
- Infection with Helicobacter pylori bacteria
- Long-term stomach inflammation (chronic gastritis)
- Pernicious anemia
- Stomach polyps
Stage 0: Cancer has not grown deeper than the mucosa (inner layer of the stomach).
Stage I: Cancer has grown beyond the mucosa (inner layer) but has not spread to the muscularis (the muscle layer) (Stage IA). In some cases, the cancer has grown into the muscularis and may or may not have spread to the lymph nodes (Stage IB).
Stage II: Cancer has grown deeper into the stomach wall and may have penetrated the muscle wall. At this stage, it may or may not have reached nearby lymph nodes.
Stage III: Cancer may have grown through all the layers of the stomach. Or it may be a smaller cancer that has spread more extensively to the lymph nodes. Distant sites, like the lung or liver are uninvolved.
Stage IV: Cancer has either spread throughout gastrointestinal tract or has spread throughout the body to distant sites.
Treatment options for gastric cancer include surgery, chemotherapy, and radiation, depending upon the cancer type, staging and patient's medical condition.
Surgery is a common treatment at all stages of gastric cancer. The following types of surgery may be used:
- Subtotal gastrectomy: Removal of the part of the stomach that contains cancer, nearby lymph nodes, and parts of other tissues and organs near the tumor. The spleen may be removed.
- Total gastrectomy: Removal of the entire stomach, nearby lymph nodes, and parts of the esophagus, small intestine, and other tissues near the tumor. The spleen may be removed. The esophagus is connected to the small intestine so the patient can continue to eat and swallow.
Chemotherapy is usually given after surgery, depending upon the cancer stage. It is frequently given in combination with radiation therapy, either before or after surgery. Chemotherapy may also be used alone in those with advanced stomach cancer to help relieve signs and symptom, i.e., palliation (not meant to be curative).
Radiation therapy can be used before surgery (neoadjuvant radiation) to shrink a stomach tumor in an attempt to eliminate microscopic cancer involvement in nearby lymph nodes and to allow greater chance of complete cancer removal during surgery. Radiation therapy can also be used after surgery (adjuvant radiation) to kill any cancer cells that might remain around the stomach. Radiation is often combined with chemotherapy. In cases of advanced cancer, radiation therapy may be used to relieve side effects caused by a large tumor, i.e., for palliation (not meant to be curative).
National Cancer Institute, Mayo Clinic, Cancer Treatment Centers of America.